Method for controlling chemical species concentration

A method for maintaining the concentrations of one or more non-time-active species in a wet chemical bath at a constant level comprising the steps of:

• a. replenishing the wet chemical bath with one or more replenishing volumes containing one or more deliberate species;
• b. determining the aggregate volume of the replenishing volumes containing the deliberate species;
• and
• c. adding an additional volume of a solution that contains all the deliberate species of the wet chemical bath at their nominal concentrations so that the total of the additional volume and an aggregate volume of the replenishing volumes is proportional to an amount of process service delivered in a time period.

A method for maintaining the concentrations of all deliberate and non-deliberate species in a wet chemical bath at a constant level comprising the steps of:

• a. replenishing the bath with one or more volumes containing one or more deliberate species;
• b. determining the aggregate volume of the replenishing volumes;
• c. adding an additional volume of a solution that contains all the deliberate species of the bath at their nominal concentrations so that the total of the additional volume and the aggregate volume is proportional to an amount of process service delivered in a time period, the time period being one of a plurality of equal time periods;
• and
• d. using the same amount of service density in the bath in each time period.

A method for maintaining the concentrations of all deliberate and non-deliberate species in a wet chemical bath at a constant level comprising the steps of:

• a. classifying the chemical species deliberately added to the bath as deliberate species;
• b. developing a material balance model by performing a material balance on each deliberate species using the stoichiometry of chemical reactions in the bath involving the deliberate species;
• c. using the material balance model to predict an amount of each deliberate species to add to the bath in order to keep each deliberate species in the bath near a target concentration;
• d. replenishing the bath with the predicted amount of the deliberate species by using one or more feed stocks that are formulated in compliance with the material balance for the deliberate species where each feed stock is dosed into the wet chemical bath in a volume proportional to a process service delivered over a time period and where a constant of proportionality for dosing is determined by the material balance;
• e. adding an additional volume of a solution that contains all the deliberate species of the wet chemical bath at their nominal concentrations so that the total of the additional volume and an aggregate volume of the replenishing volumes is proportional to an amount of process service delivered in a time period, the time period being one of a plurality of equal time periods;
• and
• f. passing the same amount of process service per unit bath volume through the bath during each time period.